Genetically modified silk fibroin nanoparticles for drug delivery: preparation strategies and application prospects

Fabrication of Silk Hydrogel Scaffolds with Aligned Porous Structures and Tunable Mechanical Properties

The effectiveness of cell culture and tissue regeneration largely depends on the structural and physiochemical characteristics of tissue-engineering scaffolds. Hydrogels are frequently employed in tissue engineering because of their high-water content and strong biocompatibility, making them the ideal scaffold materials for simulating tissue structures and properties. However, hydrogels created using traditional methods have low mechanical strength and a non-porous structure, which severely restrict their application. Herein, we successfully developed silk fibroin glycidyl methacrylate (SF-GMA) hydrogels with oriented porous structures and substantial toughness through directional freezing (DF) and in situ photo-crosslinking (DF-SF-GMA). The oriented porous structures in the DF-SF-GMA hydrogels were induced by directional ice templates and maintained after photo-crosslinking. The mechanical properties, particularly the toughness, of these scaffolds were enhanced compared to the traditional bulk hydrogels. Interestingly, the DF-SF-GMA hydrogels exhibit fast stress relaxation and variable viscoelasticity. The remarkable biocompatibility of the DF-SF-GMA hydrogels was further demonstrated in cell culture. Accordingly, this work reports a method to prepare tough SF hydrogels with aligned porous structures, which can be extensively applied to cell culture and tissue engineering.

Regenerated silk fibroin loaded with natural additives: a sustainable approach towards health care

According to World Health Organization (WHO), on average, 0.5 Kg of hazardous waste is generated per bed every day in high-income countries. The adverse effects imposed by synthetic materials and chemicals on the environment and humankind have urged researchers to explore greener technologies and materials. Amidst of all the natural fibers, silk fibroin (SF), by virtue of its superior toughness (6 × 10⁴∼16 × 10⁴ J/kg), tensile strength (47.2-67.7 MPa), tunable biodegradability, excellent Young's modulus (1.9-3.9 GPa), presence of functional groups, ease of processing, and biocompatibility has garnered an enormous amount of scientific interests. The use of silk fibroin conjoint with purely natural materials can be an excellent solution for the adverse effects of chemical-based treatment techniques. Considering this noteworthiness, vigorous research is going on in silk-based biomaterials, and it is opening up new vistas of opportunities. This review enswathes the structural aspects of silk fibroin along with its potency to form composites with other natural materials, such as curcumin, keratin, alginate, hydroxyapatite, hyaluronic acid, and cellulose, that can replace the conventionally used synthetic materials, providing a sustainable pathway to biomedical engineering. It was observed that a large amount of polar functional moieties present on the silk fibroin surface enables them to compatibilize easily with the natural additives. The conjunction of silk with natural additives initiates synergistic interactions that mitigate the limitations offered by individual units as well as enhance the applicability of materials. Further the current status and challenges in the commercialization of silk-based biomedical devices are discussed.

Progress in silk and silk fiber-inspired polymeric nanomaterials for drug delivery

The fields of drug and gene delivery have been revolutionized by the discovery and characterization of polymer-based materials. Polymeric nanomaterials have emerged as a strategy for targeted delivery because of features such as their impressive biocompatibility and improved availability. Use of naturally derived polymers in these nanomaterials is advantageous due to their biodegradability and bioresorption. Natural biopolymer-based particles composed of silk fibroins and other silk fiber-inspired proteins have been the focus of research in drug delivery systems due to their simple synthesis, tunable characteristics, and ability to respond to stimuli. Several silk and silk-inspired polymers contain a high proportion of reactive side groups, allowing for functionalization and addition of targeting moieties. In this review, we discuss the main classes of silk and silk-inspired polymers that are being used in the creation of nanomaterials. We also focus on the fabrication techniques used in generating a tunable design space of silk-based polymeric nanomaterials and detail how that translates into use for drug delivery to several distinct microenvironments.

3D printed scaffold for repairing bone defects in apical periodontitis

Objectives

To investigate the feasibility of the 3D printed scaffold for periapical bone defects.

Methods

In this study, antimicrobial peptide KSL-W-loaded PLGA sustainable-release microspheres (KSL-W@PLGA) were firstly prepared followed by assessing the drug release behavior and bacteriostatic ability against Enterococcus faecalis and Porphyromonas gingivalis. After that, we demonstrated that KSL-W@PLGA/collagen (COL)/silk fibroin (SF)/nano-hydroxyapatite (nHA) (COL/SF/nHA) scaffold via 3D-printing technique exhibited significantly good biocompatibility and osteoconductive property. The scaffold was characterized as to pore size, porosity, water absorption expansion rate and mechanical properties. Moreover, MC3T3-E1 cells were seeded into sterile scaffold materials and investigated by CCK-8, SEM and HE staining. In the animal experiment section, we constructed bone defect models of the mandible and evaluated its effect on bone formation. The Japanese white rabbits were killed at 1 and 2 months after surgery, the cone beam computerized tomography (CBCT) and micro-CT scanning, as well as HE and Masson staining analysis were performed on the samples of the operation area, respectively. Data analysis was done using ANOVA and LSD tests. (α = 0.05).

Results

We observed that the KSL-W@PLGA sustainable-release microspheres prepared in the experiment were uniform in morphology and could gradually release the antimicrobial peptide (KSL-W), which had a long-term antibacterial effect for at least up to 10 days. HE staining and SEM showed that the scaffold had good biocompatibility, which was conducive to the adhesion and proliferation of MC3T3-E1 cells. The porosity and water absorption of the scaffold were (81.96 ± 1.83)% and (458.29 ± 29.79)%, respectively. Histological and radiographic studies showed that the bone healing efficacy of the scaffold was satisfactory.

Conclusions

The KSL-W@PLGA/COL/SF/nHA scaffold possessed good biocompatibility and bone repairing ability, and had potential applications in repairing infected bone defects.

Clinical significance The 3D printed scaffold not only has an antibacterial effect, but can also promote bone tissue formation, which provides an alternative therapy option in apical periodontitis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02362-4.

Silk Fibroin As an Immobilization Matrix for Sensing Applications

The development of flexible, biocompatible, and environment-friendly sensors has attracted a significant amount of scientific interest for the past few decades. Among all the natural materials, silk fibroin (SF), due to its tunable biodegradability, biocompatibility, ease of processing, presence of functional groups, and controllable dimensions, has opened up opportunities for immobilizing multitudinous biomolecules and conformability to the skin, among other attractive opportunities. The silk fibroins also offer good physical properties, such as superior toughness and tensile strength. The sensors made of SF as an immobilization matrix have demonstrated excellent analytical performance, sensing even at low concentrations. The significant advantage of silk fibroins is the presence of functional groups along with a controllable conformation transition that enables immobilization of receptor molecules using silk fibroins as an immobilization matrix enables us to entrap the receptor molecules without using any chemical reagents. This review encompasses a detailed discussion on sensors, the advantages of using silk fibroins as an immobilization matrix for various receptors, their applications, and the future research scope in this state-of-the-art technology based upon the explorable applications for silk fibroin-based sensors.